java计算字符串中最高数字的数量

Question

我试图输出用户输入中出现最高数字的次数，例如用户输入2 4 3 4 2 4 0最高数字是4，它出现了3次，不确定如何进行

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner keyboard = new Scanner(System.in);

    String number, last;

    System.out.println("Enter an interger (0 ends the input): ");
    number = keyboard.nextLine();
    last = number.substring(number.length() - 1);

    while(!last.equals("0")){
        System.out.println("Must end the input with a 0: ");
        number = keyboard.nextLine();
        last = number.substring(number.length() - 1);
    }

    String[] array = number.split(" ");

    int max = Integer.MIN_VALUE, maxIndex = 0;

    int count;

    for (int i = 0; i < array.length; i++) {
         if (Integer.parseInt(array[i]) > max) {
             max = Integer.parseInt(array[i]);
             maxIndex = i;
         }
    }
    //String repeat = number.);
    System.out.println("The largest number is " + max);
}

Answer 1

其他答案效率较低，因此我将展示suggested solution by David Wallace的代码：

Well, the basic logic is simple. For each number in the string, there are three possibilities.

1. It's greater than the previously largest number - so store it as the largest, and reset the count to 1.
2. It's equal to the previously largest number - so increment the count.
3. It's less than the previously largest number - so ignore it.

All you need to do now is convert that to Java.

这就是：

int[] input = { 2, 4, 3, 4, 2, 4 };

int count = 0, max = 0;
for (int value : input) {
    if (count == 0 || value > max) {
        max = value;
        count = 1;
    } else if (value == max) {
        count++;
    }
}

System.out.printf("Highest number of %d was found %d times%n", max, count);

输出

Highest number of 4 was found 3 times

---

如果在很多地方都想这样做，那么可以编写自己的收集器并使用Java8流

下面是收集器的用法：

int[] input = { 2, 4, 3, 4, 2, 4 };

Max max = Arrays.stream(input).collect(Max::new, Max::add, Max::merge);

System.out.printf("Highest number of %d was found %d times%n", max.getValue(), max.getCount());

这是收藏家自己：

public class Max {
    private int value;
    private int count;
    public void add(int newValue) {
        if (this.count == 0 || newValue > this.value) {
            this.value = newValue;
            this.count = 1;
        } else if (newValue == this.value) {
            this.count++;
        }
    }
    public void merge(Max other) {
        if (this.count == 0 || (other.count != 0 && other.value > this.value)) {
            this.value = other.value;
            this.count = other.count;
        } else if (other.value == this.value) {
            this.count += other.count;
        }
    }
    public int getValue() {
        return this.value;
    }
    public int getCount() {
        return this.count;
    }
}